Installation

make_pcre is a plugin for GNU make providing ability to use Perl compatible regular expressions. It requires make 4.0 or higher (tested with 4.0 and 4.1) and libpcre3 (tested with 8.12 and 8.30).

Installation

Prerequisites

GNU make 4.x+
libpcre3 8.x+

Build

To get plugin built, simply type

$ make

in source directory. Optionally, type

$ make check

to run self-tests. Please report me if it fails on your system.

Install

Copy pcre.so into the directory where your makefile is stored.

Usage

Load the plugin by adding

load pcre.so

to your makefile.

The plugin provides two functions: pcre_find (with shorthand m) and pcre_subst (with shorthand s).

`pcre_find` function

pcre_find is similar to builtin findstring function, but it takes PCRE pattern instead substring as first argument:

$(pcre_find PATTERN,IN)
$(m PATTERN,IN)

It searches IN for matching PATTERN. If it occurs, the matched substring is returned; otherwise returned string is empty. Note that normally PATTERN is not expanded, but IN is expanded before search.

`pcre_subst` function

pcre_subst is similar to builtin subst function, but it takes PCRE pattern instead substring as first argument:

$(pcre_subst PATTERN,REPLACEMENT,TEXT)
$(s PATTERN,REPLACEMENT,TEXT)

It searches TEXT for matching PATTERN. If it occurs, the matched substring is replaced with REPLACEMENT, and the resulting string is returned. If pattern does not match, TEXT is returned unchanged. PATTERN is not expanded by default, TEXT is expanded before search, and REPLACEMENT string is expanded just before substitution.

Capturing strings

Capture by number

When matching found, both pcre_find or pcre_subst set variable $(0) to the whole matched string and variables $(1), $(2), ... to substrings captured by round brackets (like Perl does). Maximum number of strings that can be captured is 256 ($(0) to $(255)). These variables can be used until the next pcre_find or pcre_subst call that will reset them.

Capture by name

make_pcre also provides ability to set named variables to matched substrings. It can be useful if you want to preserve captured value after another matching function called or if your pattern is quite complicated, and it is difficult to handle substring numbers.

In PCRE, a subpattern can be named in one of three ways: (?<name>...) or (?'name'...) as in Perl, or (?P<name>...) as in Python. If pattern matches, variable $(name) will be set to matched substring.

Options

Both pcre_find and pcre_subst can take an optional argument consisting of one ore more characters, each of which enables some option:

$(pcre_find PATTERN,IN,ADEgimsSuUxX8)
$(m PATTERN,IN,ADEgimsSuUxX8)
$(pcre_subst PATTERN,REPLACEMENT,TEXT,ADEgimsSuUxX8)
$(s PATTERN,REPLACEMENT,TEXT,ADEgimsSuUxX8)

The following options are implemented:

A makes expression anchored, i. e. constrained to match only at the first matching point in the string. The same as in PHP;
D forces a $ metacharacter to match only before a newline at the end of the string, not before any other newlines. The same as in PHP;
E enables expansion of pattern before compilation. Note that you will need to use $$ instead $ for matching end of line in this case;
g enables global search, like in Perl. pcre_find will return space separated list of all matched substrings; pcre_subst will replace all matched substrings expanding replacement string before each substitution;
i makes search case insensitive. The same as in Perl;
m makes regexp treating string as multi-line, i. e. ^ and $ will match immediately after or immediately before internal newlines. The same as in Perl;
s forces . metacharacter to match any character including newline. The same as in Perl;
S enables additional studying of compiled regexp. The same as in PHP;
u changes the way of processing \B, \b, \D, \d, \S, \s, \W, \w and some of the POSIX character classes forcing them to use Unicode properties;
U ungreedies quantifiers by default (they still can be made greedy if followed by ?);
x forces regexp to ignore unescaped whitespaces and comments after #. The same as in Perl;
X enables extra PCRE functionality making the pattern incompatible to Perl. See PCRE documentation for additional information;
8 makes both pattern and subject string treated as UTF-8.